Method for reducing metal contamination of silicon wafers during semiconductor manufacturing

Abstract

A complex building agent, such as EDTA is added in a predetermined concentration to the "SC 1" step of a "PIRANHA-RCA" cleaning sequence for reducing the metal contamination left on the surface of a silicon wafer after completion of this cleaning step.

What is claimed is: 
     
       1. A method for reducing the metal contamination on the surface of a silicon wafer during an "RCA-clean" cleaning sequence performed on said silicon wafer in fabricating semiconductor devices therefrom, the improvement comprising: adding a complex building agent comprising of EDTA to a chemical solution containing NH 4  OH, H 2  O 2 , and H 2  provided for use in an "SC 1" cleaning step of said "RCA-clean", for providing a modified "SC 1" cleaning solution for keeping metal complexes bound in solution to substantially prevent the metal complexes from being retained on the surface of said silicon wafer, wherein the modified "SC 1" cleaning solution comprises a concentration of EDTA ranging from about 0.05 mg/l to about 0.10 mg/l;   retaining said modified "SC 1" cleaning solution in a tank tool; and   submerging said silicon wafer in said modified "SC 1" cleaning solution, for a selected period of time during an "SC 1" step of said improved "RCA-clean".   
     
     
       2. The method of claim 1, wherein the concentration of EDTA is about 0.10 mg/l, for addition to an "SC 1" original formula containing about 4% by weight of NH 4  OH, and about 5% by weight of H 2  O 2 . 
     
     
       3. The method of claim 1, wherein the concentration of EDTA is about 0.05 mg/l, for addition to an "SC 1" dilute formula containing about 0.004% by weight of NH 4  OH, and about 0.003% by weight of H 2  O 2 . 
     
     
       4. A method for reducing the metal contamination on the surface of a silicon wafer during an "RCA-clean" cleaning sequence performed on said silicon wafer in fabricating semiconductor devices therefrom, the improvement comprising: adding from a complex building agent comprising amine substituted phosphates to a chemical solution containing NH 4  OH, H 2  O 2 , and H 2  O provided for use in an "SC 1" cleaning step of said "RCA-clean", for providing a modified "SC 1" cleaning solution for keeping metal complexes bound in solution to substantially prevent the metal complexes from being retained on the surface of said silicon wafer, wherein the modified "SC 1" cleaning solution comprises a concentration of amine substituted phosphates ranging from about 0.10 mg/l to about 0.30 mg/l   retaining said modified "SC 1" cleaning solution in a tank tool; and   submerging said silicon wafer in said modified "SC 1" cleaning solution, for a selected period of time during an "SC 1" step of said improved "RCA-clean".   
     
     
       5. The method of claim 4, wherein the concentration of said amine substituted phosphates is about 0.30 mg/l for addition to an "SC 1" original formula containing about 4% by weight of NH 4  OH, and about 5% by weight of H 2  O 2 . 
     
     
       6. The method of claim 4, wherein the concentration of said amine substituted phosphates is about 0.10 mg/l, for addition to an "SC 1" dilute formula containing about 0.004% by weight of NH 4  OH, and about 0.003% by weight of H 2  O 2 . 
     
     
       7. A modified cleaning solution for improving the "SC 1" cleaning step of an "RCA-clean" sequence for silicon wafers, the modified cleaning solution comprising a modified "SC 1" cleaning formulation comprising NH 4  OH, H 2  O 2 , water, and a complex building agent comprising of EDTA for keeping metal complexes bound in solution during the "SC 1" step of cleaning said silicon wafers, thereby substantially reducing metal contamination of surfaces of said silicon wafers, and wherein the modified "SC 1" solution comprises a concentration of EDTA ranging from about 0.05 mg/l to about 0.10 mg/l. 
     
     
       8. The modified "SC 1" cleaning solution of claim 7, wherein the concentration of EDTA is about 0.10 mg/l, for an "SC 1" original formula containing about 4% by weight of NH 4  OH, and about 5% by weight of H 2  O 2 . 
     
     
       9. The modified "SC 1" cleaning solution of claim 7, wherein the concentration of EDTA is about 0.05 mg/l, for an "SC 1" dilute formula containing about 0.004% by weight of NH 4  OH, and about 0.003% by weight of H 2  O 2 . 
     
     
       10. A modified cleaning solution for improving the "SC 1" cleaning step of an "RCA-clean" sequence for silicon wafers, the modified cleaning solution comprising a modified "SC 1" cleaning formulation comprising NH 4  OH, H 2  O 2 , water, and a complex building agent comprising amine substituted phosphates for keeping metal complexes bound in solution during the "SC 1" step of cleaning said silicon wafers, thereby substantially reducing metal contamination of surfaces of said silicon wafers, and wherein the modified "SC 1" solution comprises a concentration of amine substituted phosphates ranging from about 0.10 mg/l to about 0.30 mg/l. 
     
     
       11. The modified "SC 1" cleaning solution of claim 10, wherein the concentration of amine substituted phosphates is about 0.03 mg/l for an "SC 1" original formula containing about 4% by weight of NH 4  OH, and about 5% by weight of H 2  O 2 . 
     
     
       12. The modified "SC 1" cleaning solution of claim 10, wherein the concentration of amine substituted phosphates is about 0.10 mg/l for an "SC 1" dilute formula comprising about 0.004% by weight of NH 4  OH, and about 0.003% by weight of H 2  O 2 . 
     
     
       13. The modified "SC 1" cleaning solution of claim 7, wherein said complex building agent comprises a concentration of EDTA ranging from about 0.05 mg/l to about 0.10 mg/l for concentrations of NH 4  OH ranging from about 0.004% by weight to about 4% by weight, respectively, and of H 2  O 2  ranging from about 0.003% by weight to about 5% by weight, respectively. 
     
     
       14. The modified "SC 1" cleaning solution of claim 10, wherein said complex building agent comprises a concentration of amine substituted phosphates ranging from about 0.10 mg/l to about 0.30 mg/l, for concentrations of NH 4  OH ranging from about 0.004% by weight to about 4% by weight, respectively, and of H 2  O 2  ranging from about 0.003% by weight to about 5% by weight, respectively.